Waterjet-guided laser machine with inline optical feedback control

Abstract

A waterjet-guided laser machine includes a laser source, an LED, a waterjet head, and a light sensor. The waterjet head includes a water inlet and a nozzle having an outlet for a discharging a waterjet. There is a laser optical path along which a pulsed laser beam travels to the nozzle outlet. There is also a light beam optical delivery path along which the light beam travels from the LED to the nozzle outlet. The light beam optical delivery path is coincident with the laser optical path in the nozzle. There is a light beam optical return path along which the light beam that is reflected off of a workpiece travels to the light sensor. The light beam optical return path is coincident with the laser optical path inside the nozzle and coincident with the light beam optical delivery path inside the nozzle.

What is claimed is: 
     
         1 . A waterjet-guided laser machine comprising:
 a laser source operable to emit a pulsed laser beam;   a light-emitting diode (LED) operable to emit a light beam different than the pulsed laser beam;   a waterjet head including an inlet for receiving water and a nozzle having an outlet for a discharging a jet of the water therefrom;   a light sensor;   a laser optical path along which the pulsed laser beam travels from the laser source, through the nozzle and to the nozzle outlet;   a light beam optical delivery path along which the light beam travels from the LED, through the nozzle and to the nozzle outlet, the light beam optical delivery path being coincident with the laser optical path inside of the nozzle; and   a light beam optical return path along which a portion of the light beam that is reflected off of a workpiece travels from the nozzle outlet and back through the nozzle to the light sensor, the light beam optical return path being coincident with the laser optical path inside the nozzle and coincident with the light beam optical delivery path inside the nozzle.   
     
     
         2 . The waterjet-guided laser machine as recited in  claim 1 , wherein the laser optical path contains, in order from the laser source to the waterjet head, a first lens, a first mirror, a second mirror, and a second lens. 
     
     
         3 . The waterjet-guided laser machine as recited in  claim 2 , wherein the light beam optical delivery path is coincident with the with the laser optical path from the second mirror to the second lens and from the second lens to the waterjet head, and the laser optical path is non-coincident with the with the light beam optical delivery path from the laser source to the first lens, from the first lens to the first mirror, and from the first mirror to the second mirror. 
     
     
         4 . The waterjet-guided laser machine as recited in  claim 2 , wherein the light beam optical return path is coincident with the with the laser optical path from the waterjet head to the second lens, from the second lens to the second mirror, and from the second mirror to the first mirror. 
     
     
         5 . The waterjet-guided laser machine as recited in  claim 4 , wherein the light beam optical return path includes a third mirror, and the light beam optical return path is non-coincident with the laser optical path from the first mirror to the third mirror and from the third mirror to the light sensor. 
     
     
         6 . The waterjet-guided laser machine as recited in  claim 1 , wherein the LED is operable to emit the light beam having a wavelength of 495-570 nanometers. 
     
     
         7 . The waterjet-guided laser machine as recited in  claim 1 , further comprising an electronic controller operably connected with at least the laser source, the LED, and the light sensor. 
     
     
         8 . The waterjet-guided laser machine as recited in  claim 7 , wherein the light sensor is operable to emit sensor signals responsive to the portion of the light beam received into the light sensor from the light beam optical return path, and the electronic controller is configured to determine from the sensor signals a depth-of-cut of the laser beam into the workpiece. 
     
     
         9 . The waterjet-guided laser machine as recited in  claim 8 , wherein the electronic controller is configured to adjust scan rate of movement of the laser beam relative to the workpiece along a cutting path based upon the depth-of-cut. 
     
     
         10 . The waterjet-guided laser machine as recited in  claim 8 , wherein the electronic controller is configured to identify a fault condition if the depth-of-cut is below a threshold over a preset duration. 
     
     
         11 . The waterjet-guided laser machine as recited in  claim 7 , wherein the electronic controller is configured to pulse the light beam in coordination with the pulsed laser beam such that during an OFF period of the pulsed laser beam the light beam is ON and during an ON period of the pulsed laser beam the light beam if OFF. 
     
     
         12 . The waterjet-guided laser machine as recited in  claim 7 , further comprising an acoustic sensor operable to emit acoustic sensor signals responsive to receiving sound emitted from the workpiece, and the electronic controller is configured to determine an initiation of cutting of the workpiece by the laser based on the acoustic sensor signals. 
     
     
         13 . The waterjet-guided laser machine as recited in  claim 12 , wherein the electronic controller is configured to determine the initiation of the cutting of the workpiece by the laser based on the frequency of the acoustic sensor signals. 
     
     
         14 . A method of machining a workpiece, the method comprising:
 in a waterjet-guided laser machine:   discharging a jet of water from a nozzle outlet of a waterjet head, the jet impinging the workpiece;   emitting a pulsed laser beam from a laser beam source along a laser optical path through the nozzle and to the nozzle outlet such that the pulsed laser beam is guided in the jet of water and also impinges the workpiece;   emitting a light beam that is different than the laser beam from a light-emitting diode (LED) along a light beam optical delivery path through the nozzle and to the nozzle outlet, the light beam optical delivery path being coincident with the laser optical path inside of the nozzle;   receiving into a light sensor a portion of the light beam that is reflected off of the workpiece along a light beam optical return path from the nozzle outlet and back through the nozzle, the light sensor emitting sensor signals responsive to the portion of the light beam that is received, the light beam optical return path being coincident with the laser optical path inside the nozzle and coincident with the light beam optical delivery path inside the nozzle; and   using the sensor signals as feedback in an electronic controller to adaptively adjust the cutting of the workpiece by the laser beam.   
     
     
         15 . The method as recited in  claim 14 , wherein the electronic controller determines from the sensor signals a depth-of-cut of the laser beam into the workpiece. 
     
     
         16 . The method as recited in  claim 15 , wherein the electronic controller adjusts a scan rate of the movement of the laser beam relative to the workpiece along a cutting path based upon the depth-of-cut. 
     
     
         17 . The method as recited in  claim 15 , wherein the electronic controller identifies a fault condition if the depth-of-cut is below a threshold over a preset duration. 
     
     
         18 . The method as recited in  claim 14 , wherein the electronic controller pulses the light beam in coordination with the pulsed laser beam such that during an OFF period of the pulsed laser beam the light beam is ON and during an ON period of the pulsed laser beam the light beam if OFF.